1828 W. Carr (ed. 2) (at cited word) From the Lat. præcox, soon, over hastie or rash ripe.
1886 R. E. G. Cole Rash or Rash-ripe, Said of grain in the ear, when it is over ripe and falls out easily.
1995 J. M. Sims-Kimbrey 241/2 Rash-ripe, over-ripe. Used of fruit etc. that should have been picked long ago.